1. Field of the Invention
The present invention relates to an exhaust gas purifying apparatus for an automobile diesel engine.
2. Description of the Prior Art
Diesel particulates (i.e., soot and dust particles) are contained in exhaust gases emitted from diesel engines of buses, tracks or the like. The diesel particulates have been causing serious problems recently, such as environmental contaminations and damages to human health. In order to solve the problems, the combustion manner of the diesel engines has been improved, or a ceramic filter has been employed.
However, the diesel engines are subjected to a wide variety of operations, such as cold starting, hill climbing, heavy loading or the like. Accordingly, it is hard to reduce the diesel particulates sharply by improving the combustion manner.
On the other hand, when the ceramic filter is employed to adsorb the diesel particulates, the exhaust gas pressure loss increases and the engine efficiency decreases by the pressure loss. In particular, in the case that an amount of the adsorbed diesel particulates increases, the exhaust gas pressure loss increases in an accelerating manner, and accordingly the output of the diesel engine and the combustion characteristic deteriorate, thereby generating extra diesel particulates. In addition, the ceramic filter must be enlarged in order to reduce the exhaust gas pressure loss. Hence, it is difficult to put the ceramic filter into a practical application in view of the cost and the space.